594 GLOSSARY. 



Applied formerly to the PhysopJioridce, an order of Oceanic Hydrozoa, in 



which a "float" is present. 

 PHYSOPHORID^E (Gr. phusa, air-bladder ; and phero, I carry). An order of 



Oceanic Hydrozoa. 



PHYTOID (Gr. phufon, : Si plant; and eidos, form). Plant-like. 

 PHYTOPHAGOUS (Gr. pJiuton, a plant ; and phago, I eat). Plant-eating, or 



herbivorous. 

 PINNATE (Lat. pinna, a feather). Feather-shaped, or possessing lateral pro- 



siaccaa 



PlNNlGRADA (Lat. pinna, a feather ; gradior, I walk). The group of Carni- 

 vora comprising the Seals and Walruses, adapted for an aquatic life. Often 

 called Pinnipedia. 



PINNULE (Lat. dim. of pinna). The lateral processes of the arms of Crinoids. 



PISCES (Lat. piscis, a fish). The class of Vertebrates comprisitig the Fishes. 



PLACENTA (Lat. a cake). The "after-birth," or the organ by which a vascu- 

 lar connection is established in the higher Mammalia between the mother 

 and the foetus. 



PLACENTAL. Possessing a placenta ; or connected with the placenta. 



PLACOID (Gr. plax, a plate ; eidos, form). Applied to the irregular bony 

 plates, grains, or spines which are found in the skin of various fishes (Elas- 

 mobranc/tii). 



PLAGIOSTOMI (Gr. plagios, transverse ; stoma, mouth). The Sharks and Rays, 

 in which the mouth is transverse, and is placed on the under surface of the 

 head. 



PLANARIDA (Gr. plane, wandering). A sub-order of the Turbellaria. 



PLANTIGRADE (Lat. planta, the sole of the foot ; gradior, I walk). Applying 

 the sole of the foot to the ground in walking. 



PLANULA (Lat. planus, flat). The oval ciliated embryo of certain of the Hy- 

 drozoa. 



PLASTRON. The lower or ventral portion of the bony case of the Chelonians. 



PLATYELMIA (Gr. platus, broad ; and helmins, an intestinal worm). The 

 division of Scolecida comprising the Tapeworms, &c. 



PLATYRHINA (Gr. platus, broad ; rhines, nostrils). A group of the Quadrumana. 



PLEURA (Gr. the side). The serous membrane covering the lung in the air- 

 breathing Vertebrates. 



PLEURON (Gr. pleiiron, a rib). The lateral extensions of the shell of Crustacea. 



PLUTEUS (Lat. a pent-house). The larval form of the Echinoidea. 



PNEUMATIC (Gr. pneuma, air). Filled with air. 



PNEUMATOCYST (Gr. pneuma, air ; and Jcustis, cyst). The air-sac or float of 

 certain of the Oceanic Hydrozoa (PhysopJioridce). 



PNEUMATOPHORE (Gr. pneuma, air ; and phero, I carry). The proxima 

 dilatation of the coenosarc in the Physophoridce which surrounds the 

 pneumatocyst. 



PNEUMOSKELETON (Gr. pneuma; and skeletos, dry). The hard stnictures 

 which are connected with the breathing organs (e.g., the shell of Molluscs). 



PODOPHTHALMATA (Gr. pous, foot; and ophthalmos, eye). The division of 

 Crustacea in which the eyes are borne at the end of long foot-stalks. 



PODOSOMATA (Gr pous, foot ; soma, body). An order of Arachnida. 



POEPHAGA (Gr. poe, grass ; phago, I eat). A group of the Marsupials. 



POLLEX (Lat. the thumb). The innermost of the five normal digits of the 

 anterior limb of the higher Vertebrates. In man, the thumb. 



POLYCYSTINA (Gr. polus, many ; and kustis, a cyst). An order of Protozoa, 

 with foraminated siliceous shells. 



POLYGASTRICA (Gr. j)olus ; and gaster, stomach). The name applied by 

 Ehrenberg to the Infusoria, under the belief that they possessed many 

 stomachs. 



POLYPARY. The hard chitinous covering secreted by many of the Hydrozoa. 



POLYPE (Gr. polus, many ; pous, foot). Restricted to the single individual of 

 a simple ActinozoSn, such as a Sea-anemone, or to the separate zoouis of a 

 compound Actinozoon. Often applied indiscriminately to any of the Ccelen- 

 terata, or even to the Polyzoa. 



